Myosin is a motor that runs along (or tugs at) actin. Actin-based movement of vesicles Chromosome migration Myosin-driven cell shape changes Muscle contraction.

Slides:

Advertisements

Similar presentations

Advertisements

Skeletal Muscle Activity: Contraction

Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Twitch time course Duration of twitch is largely governed by rate of sequestration.

Neuromuscular Junction

Sliding Filament Theory

Destruction of Acetylcholine

The Steps of Muscle Contraction: The Sliding Filament Theory

Muscles n Skeletal muscle organization and how it contracts.

Sliding Filament Theory Review

Warm-Up 4/8/15 1.What is an autoimmune disorder? 2.What how are LEMS and MG similar? 3.How are LEMS and MG different? Test - Tuesday.

Figure  _________ and_______filaments slide over each other______________the muscle length  Always requires ________ ions and ___.

09_10 Sliding filament theory Slide number: 1 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Tropomyosin.

Muscle tissue and muscle contraction Rosalie Crawford - Veronica Revel Fondazione Liceo Linguistico Courmayeur CLIL SCIENCE.

Lecture 12 - The actin cytoskeleton

Excitation-Contraction Coupling

Motor mechanisms. Keywords (reading p ) Bundle, fiber, myofibril, sarcomere Z-line, thick filament, thin filament Actin, myosin, sliding filament.

Lecture 12 - The actin cytoskeleton. Actin filaments allow cells to adopt different shapes and perform different functions VilliContractile bundles.

Contraction of skeletal muscle. Learning objectives What evidence supports the sliding filament mechanism of muscle contraction? How does the sliding.

Sliding Filament Theory

Myosin Myosin is a protein molecule found in the thick filaments. Myosin is a protein molecule found in the thick filaments.

Muscle Physiology.

1 Skeletal muscle structure fig 9-1a striated long multinucleate cells extend from tendon to tendon formed by fusion of myoblasts innervated by somatic.

 Name the following movements: ◦ Increasing angle of joint (ex. Straightening arm) ◦ Moving around longitudinal axis: ◦ Moving a limb away from midline.

MUSCLE CONTRACTION. Microscopic Anatomy of Skeletal Muscle Sarcomere Contractile unit of a muscle fiber Figure 6.3b.

Muscle Contraction. Muscle Movement Muscle fiber must be stimulated: – By an electrical signal called muscle action potential (AP) – Delivered by motor.

Muscle Cells & Muscle Fiber Contractions

Muscle Physiology.

Cytoskeltal Motors. Network of long protein strands located in the cytosol not surrounded by membranes Consist of microtubules and microfilaments Microfilaments.

Hair cells, actin bundles, and unconventional myosins.

The Molecular Motor Myosin

Bundle of fibers Muscle fiber (muscle cell) Myofibril Sarcomere.

IN CLASS NOTES = STEPS OF A MUSCLE CONTRACTION. STEP 1 Calcium ions present Ca+ binds to troponin which makes tropomyosin move out of way for myosin head.

Motor mechanisms.

Non-striated Muscle I. Locations of non-striated muscle in vertebrate body GI tract (including internal, but not external sphincters) Blood vessels and.

Interaction of thick & thin filaments __________________ –_____________________________________ _____________________________________ –_____________________________________.

____ Chapter 49 ~ Sensory and Motor Mechanisms ( Just focusing on motor mechanisms ) Motor Mechanisms.

Sliding Filament.

Synapse – The site of connection between a neuron and a cell. Neurotransmitter – A chemical released at the neuron’s synapse that communicates with the.

II. Skeletal Muscle Overview A. Skeletal Muscle Distinguishing Characteristics Striated Voluntary Multi-nucleated B. Functions Movement Maintain Posture.

Muscles & Motor Locomotion Why Do We Need All That ATP?

The Sliding Filament Theory

Figure 10.6 Levels of Functional Organization in Skeletal Muscle Fiber

MICROFILAMENTS AND INTERMEDIATE FILAMENTS BY PRIANKA RAJAN.

Contraction Mechanism Actin and myosin interact via to the sliding filament mechanism Resting State –Actin bound by caldesmon –Myosin light chain (MLC)

Lecture #21 Date ____ n Chapter 49 ~ Sensory and Motor Mechanisms.

Molecular Basis of Muscle Contraction Mercedita Macalintal, MD, DPPS.

Molecular Basis of Muscle Contraction Standard 9 h. Students know the cellular and molecular basis of muscle ocntraction,including the roles of actin,

Muscle Contraction. 1.Acetylcholine (Ach) is released from the axon terminal (nerve) into the synaptic cleft and binds to Ach receptors in the sarcolemma.

Muscle voluntary, striated involuntary, striated auto-rhythmic involuntary, non-striated evolved first multi-nucleated digestive system arteries, veins.

Muscle Contraction.

How do muscle cells contract ?. What is the structure of a muscle fiber ? The sarcolemma, or plasma membrane contains invaginations called T (transverse)

Musculoskeletal System & Movement

Muscles Skeletal muscles are stimulated to contract by nerves and act as effectors.

Muscle contraction.

Sliding Filament Theory

Initially Sarcolemma is in the Resting Membrane state

Molecular mechanism of muscle contraction

A simplified diagram of smooth muscle contraction and the site of action of calcium channel-blocking drugs. Contraction is triggered (red arrows) by influx.

The Structure of Skeletal Muscle

Comparative Vertebrate Physiology

Muscle Contraction.

Chapter 3 Support and locomotion – muscles and movement.

NOTES: The Muscular System (Ch 8, part 2)

Muscle and Muscle Contraction

Skeletal muscle contraction

Contraction II Department of Biology, WCU.

Sliding Filament Theory

Presentation transcript:

Myosin is a motor that runs along (or tugs at) actin. Actin-based movement of vesicles Chromosome migration Myosin-driven cell shape changes Muscle contraction

All myosins have head(s), neck and tails 13 family members in humans But know Myosin I, II, and V Head has ATPase and actin binding domains, actin accelerates ATPase Neck regulates the head, light chains bind calcium Tails have specific binding sites Gentle digestion releases domains

Myosin II

Experimental tools for your toolbox: Sliding filament assay, Optical trap ATP requirement, conditions, direction, rates, force movement in discrete steps (cog wheel)

Know the contraction cycle!! 1.No ATP- rigor state 2.ATP causes release and movement 3.ATP hydrolysis allows rebinding 4.Loss of Pi causes power stroke 5.ADP release restores to rigor position

The myosin-actin interaction drives muscle contraction Muscles have the power of a car on a per mass basis Skeletal, isotonic contractions Smooth, isometric contraction

Tropomyosin, ropelike protein binds actin. Troponin, binds TM and calcium Calcium binding nudges TM TM movement exposes myosin site on actin With myosin able to bind, the contraction cycle proceeds

Smooth and skeletal contractions differ Instead of troponin, smooth muscles use caldesmon at low calcium Calcium levels change more slowly The network is less ordered.

Caldesmon binds Caldesmon off by CaM Additional control by kinases

It’s also possible to control contraction by myosin modification Examples: 1. Invertebrate muscle, calcium binding to myosin LC 2. Vertebrate smooth muscle, phosphorylation of myosin LC by MLCK in a Ca++/CM cycle 3. Or by Rho kinase These pathways are independent of the action potential. They represent other signaling pathways.